The objective is to investigate whether the intracellular concentrations of melphalan and chlorambucil are sensitive to transmembrane ion gradients and whether enhanced drug accumulation by tumor cells can be achieved by thermally-induced changes in transmembrane potential and component ion gradients. The specific aims are: (1) Identification and characterization of membrane potential and ion gradient dependent melphalan and chlorambucil transport processes at normal physiological temperature in murine L1210 cells (melphalan-sensitive and resistant cell lines), hamster splenocytes, SV40-transformed hamster lymphoid (GD248) cells and plasma membrane vesicles from these cells, to include: (a) Na+ and K+ dependency; sensitivity to electrogenic and non-electrogenic ionophores, and ouabain; (b) Cell environmental factors such as pH, amino acids and bicarbonate and (c) Studies with isolated membrane vesicles to establish metabolic dependency of transport; vesicles with artifically applied ion gradients or vesicles with entrapped ATP-regenerating systems to form ion gradients will be used. (2) Characterization of melphalan and chlorambucil transport in L1210 and hamster lymphoid cells and isolated membrane vesicles at hyperthermic temperatures (39-42 C) in terms of: (a) Energy and ion gradient dependent and independent transport processes as described in specific aim #1; (b) Reversibility of heat-induced changes in drug transport and (c) Correlation of thermally enhanced drug accumulation and cell growth by cell survival and analysis with L1210 cells and DNA synthesis as measured by 3H-thymidine incorporation with hamster splenocytes and GD248 cells.